Trust isn't something you can ever establish in a forum environment, so there's no point trying to convince people that don't care in the first place.
I mean just because they're being skeptical doesn't mean they don't care about your ideas. Even if you try to to contact VC or something similar I'm sure they'll ask you tons of questions too. Besides, who's to say some whales don't lurk around in this forum trying to find a start-up to burn their money? Being dismissive would reduce the chance for them to notice your project. It's worth it to provide a short whitepaper explaining your ideas and your portfolio here. You can reuse those materials for other channels if you want to.